Valve

ABSTRACT

There is disclosed a heart valve prosthesis having a configuration such that blood flow through it has a helical flow pattern such as to substantially reduce or eliminate turbulence and dead flow regions in the blood flow.

[0001] This invention relates to valves, and especially, though notexclusively, to one-way valves, more particularly for use in clinicalsituations and most particularly to heart valve prostheses.

[0002] Heart valve prostheses comprise one-way valves which areimplanted in place of diseased or defective natural valves and are madeof bio-compatible materials such as stainless steel and certain plasticsas well as material harvested from other animals, such as pigs. Bothflap valves and ball valves are known. Flap valves comprise one or twoflexible plastics material flaps seating on a ledge in a valve annulusor on each other. Ball valves have a ball movable in a cage seatingagainst a portion of a valve annulus. Some valves emulate human heartvalves by comprising multiple cusps or leaflets.

[0003] Heart valve prostheses are designed according to a number ofdesign considerations. One consideration is clearly durability andfunctionality over a long period of time. Another is ease ofimplantation, and valves are designed both for open-chest surgery andso-called keyhole surgery avoiding the major trauma of open-chestsurgery. By and large, valve materials are smooth and configurations arerounded or streamlined to avoid undue disturbance to the blood flow whenopen, but limitations of the materials used and the need for suturing inplace militate against a perfect replica being made of a natural valve.

[0004] It has been proposed to design blood flow tubing, such asvascular prostheses, in such a way as to improve blood flow and reduceturbulence and dead flow areas, where blood vessel lining can be damagedleading to narrowing and occlude flow or even form thromboses. Whilesuch improvement is welcome, its beneficial effects can be reduced oreven reversed by locations in the vascular system where such improvementis not present.

[0005] One such location could be a prosthetic heart valve, which might,despite design measures to the contrary, induce a wholly or partlydifferent flow pattern to that produced by a natural healthy valve, andthe manner of attachment may further affect the flow adversely.

[0006] The invention provides a heart valve which does not suffer, atleast to the same extent as conventional valve, the problems ofdeleterious flow interference or alteration.

[0007] The invention comprises a heart valve having a configuration suchthat blood flow through it has a helical flow pattern such as tosubstantially reduce or eliminate turbulence and/or dead flow regions inthe blood flow.

[0008] The flow pattern may be similar to, if not exactly the same ashelical flow patterns observed in normal blood vessels.

[0009] The invention can also have impact in valves other than heartvalves and in flows of fluid other than blood.

[0010] The valve may induce a helical flow in the blood entering and/orleaving the valve.

[0011] The valve may have an internal helical configuration.

[0012] The valve may be a flap valve, and may then have flap meanswhich, when open, adopt a helical configuration. By “helical” is meantgenerally, rather than mathematically precisely helical, of course.

[0013] A flap valve may have a single flap seated on a helical valveseat, having hinging inclined to the general flow direction. Or it mayhave a pair of cooperating flaps hinged on skew hinges and twisted tomate in the closed configuration and opening so that they formcomplementary flow-directing vanes.

[0014] A flap valve may have a plurality of cooperating flaps, cusps orleaflets mating in an iris-like configuration and opening so as to formcomplementary flow-directing vanes, each having hinging inclined to thegeneral flow direction.

[0015] The hinging may comprise a defined hinge line formed by a linearthinned portion of flap material, or may comprise a thin flexible regionof flap material which arcs smoothly on opening.

[0016] The valve may be a ball valve, which may have a valve seatcomprising vane means having a helical configuration.

[0017] Embodiments of heart valves according to the invention will nowbe described with reference to the accompanying drawings, in which:

[0018]FIG. 1 is a side elevation of a first embodiment;

[0019]FIG. 2 is an elevation on Arrow 2 of FIG. 1;

[0020]FIG. 3 is a plan on Arrow 3 of FIG. 1;

[0021]FIG. 4 is a side elevation of a second embodiment;

[0022]FIG. 5 is an elevation on Arrow 5 of FIG. 4;

[0023]FIG. 6 is a plan on Arrow 6 of FIG. 4;

[0024]FIG. 7 is a section through flap material illustrating a firstform of hinging;

[0025]FIG. 8 is a section like FIG. 7 illustrating a second form ofhinging;

[0026]FIG. 9 is a side elevation of a third embodiment; and

[0027]FIG. 10 is a view on Arrow 10 of FIG. 9.

[0028] The drawings illustrate heart valves 11 having a configurationsuch that blood flow through them has a helical flow pattern such as tosubstantially reduce or eliminate turbulence and/or dead flow regions inthe blood flow.

[0029] The valves 11 induce a helical flow in the blood entering and/orleaving the valve, and have an internal helical configuration.

[0030] FIGS. 1 to 6 illustrate flap valves 11, having flap means 12which, when open, adopt a helical configuration. By “helical” is meantgenerally, rather than mathematically precisely helical, of course. Inthe drawings, the open position is shown in solid line, the closedposition in broken line.

[0031] The valve illustrated in FIGS. 1 to 3 has a single flap 12 seatedon a helical valve seat 13 having hinging 14 inclined to the generalflow direction, arrow 15. When the valve is open, the flap imparts arotational element to the flow.

[0032] The valve illustrated in FIGS. 4 to 6 has a pair of cooperatingflaps 12 a, 12 b hinged on skew 14 a, 14 b hinges respectively andtwisted to mate in the closed configuration and opening so that theyform complementary flow-directing vanes. More complex flap valves, notshown, in accordance with the invention, have a plurality of cooperatingflaps mating in an iris-like configuration and opening so as to formcomplementary flow-directing vanes, each having hinging inclined to thegeneral flow direction.

[0033] Different methods of hinging are illustrated in FIGS. 7 and 8.FIG. 7 illustrates hinging 14 comprising a defined hinge line 16 formedby a linear thinned portion of flap material, while FIG. 8 illustrateshinging 14 comprising a thin flexible region 17 of flap material whicharcs smoothly on opening.

[0034]FIGS. 9 and 10 illustrate a ball valve 11 which has a valve seat91 comprising vane means 92 having a helical configuration. As shown,there are four vanes 91, though, of course, three would suffice and morethan four would be possible. The ball 93 is movable within a cage formedpartially by the vanes 92 and is forced away from the vanes 92 bypressure of blood entering the valve through the vanes 92 and is forcedback by a resilient member, not shown, between the ball and thedownstream retaining ring of the cage.

[0035] The helical flow induced by the flap or vane means in the variousembodiments can be arranged, by suitable choice of the configuration, toreduce turbulence and/or dead flow regions in the bloodstream local tothe valve. Care will clearly be taken not to introduce any such adverseflow characteristics by attention to streamlining of all components ofthe valve.

[0036] As mentioned above, whilst the avoidance of turbulence and deadflow regions has recently become of significance in the prevention ofvascular problems leading to heart attacks and strokes, hence thedescription herein particularly of heart valves, the reduction of suchadverse flow characteristics in other flow systems can also beimportant, and valves may be made after the fashion of the heart valvesabove described for such systems as chemical engineering plant, fuelpipelines and laboratory equipment.

[0037] And, while the valves above described are all one-way or checkvalves and passive inducers of helical flow, controlled, e.g. solenoidcontrolled or actuator controlled, valves may be configured for helicalflow, and active inducement can be contemplated. For example, a ballvalve which is electromagnetically operated my also have a rotatingball, rotated, say, by electromagnetic induction, which will inducehelical flow and which has the additional advantage of beingcontrollable as to the amount of helical component is to be induced,simply by controlling the rate of revolution of the ball.

1. A heart valve prosthesis having a configuration such that blood flowthrough it has a helical flow pattern such as to substantially reduce oreliminate turbulence and dead flow regions in the blood flow
 2. Aprosthesis according to claim 1, inducing a helical flow in the bloodexiting the valve.
 3. A prosthesis according to claim 1 or claim 2,having an internal helical formation.
 4. A prosthesis according to anyone of claims 1 to 3, being a flap valve.
 5. A prosthesis according toclaim 4, having a flap means which, when open, adopt a helicalconfiguration.
 6. A prosthesis according to claim 5, having a singleflap seated on a helical valve seat, having hinging inclined to thegeneral flow direction.
 7. A prosthesis according to claim 5, having apair of cooperating flaps mating in a yin-yang configuration and openingso that they form complementary flow directing vanes, each havinghinging inclined to the general flow direction.
 8. A prosthesisaccording to claim 5, having a plurality of cooperating flaps mating inan iris-like configuration, and opening so as to form complementaryflow-directing vanes, each having hinging inclined to the general flowdirection.
 9. A prosthesis according to any one of claims 5 to 8, inwhich the hinging comprises a defined hinge line formed as a linear,thin, flexible portion of flap material.
 10. A prosthesis according toany one of claims 5 to 8, in which the hinging comprises a thin flexibleregion of flap material which arcs smoothly on opening.
 11. A prosthesisaccording to any one of claims 1 to 3, being a ball valve.
 12. Aprosthesis according to claim 11, having a valve seat comprising vanemeans having a helical configuration.